The present invention relates generally to electric motors, and particularly to a modular stator assembly that facilitates motor construction.
Submersible electric motors are used in submersible pumping systems to lift wellbore fluids from depths of up to several thousand feet. A conventional motor used to provide the equivalent pumping power on the surface cannot be used in a wellbore because the diameter of such a motor would be too wide to fit into the wellbore. Therefore, as compared to short, thick surface motors, the stators of submersible electric motors are relatively thin and extremely elongated.
Elongating the stator allows the motor to produce the required torque to drive a pump by developing magnetic force over a stator of a much larger length. Thus, if long enough a motor that produces a relatively smaller torque per foot can produce a sufficient total torque. Depending on the horsepower required of the motor, electric submersible pumping system motors can utilize stator assemblies thirty feet long or more. Preparation of the stator windings requires long, thin polished rods that serve as needles for pulling the insulated, conductor wires through a lengthy assembly of stator laminations. This conventional process is a comparatively slow and expensive process for manufacturing such motors. Additionally, repair or rebuilding of such motors often requires complete destruction or tear down of the motor with little component repair value due to the unitary stator assembly.
It would be advantageous to have a modular stator that could be used to construct motors, such as motors utilized in electric submersible pumping systems. Benefits of such a modular construction would include reduced cost and assembly time, reduced repair time and reduced motor component inventory.
The present invention features an electric motor with a modular stator. The modular stator comprises a plurality of stator sections and a rotor disposed within the stator sections. The stator sections are mechanically and electrically coupleable to form a stator of a desired length. According to additional aspects of the invention, a submersible pumping system is provided that utilizes an electric motor with a modular stator assembly.
According to another aspect of the invention, a method is provided for facilitating the assembly of an electric motor. The method includes manufacturing a plurality of stator sections wherein each stator section is mechanically and electrically coupleable to another stator section. The stator sections include a top stator section electrically coupleable to a source of electric power, a middle stator section with conductors extending longitudinally therethrough, and a bottom section with conductors. When coupled, the stator sections complete a conductive loop through the stator sections to the source of electric power.
The method includes determining the desired motor length for a given application and assembling a top section, a bottom section, and an appropriate number of middle sections to form a stator of the desired length. The method further includes assembling the stator sections and disposing a rotor within the stator sections.